Refactor the JNI interface to make it more modular and maintainable (#802)

sherpa-onnx/kotlin-api/OnlineStream.kt

@@ -0,0 +1,27 @@
+package com.k2fsa.sherpa.onnx
+
+class OnlineStream(var ptr: Long = 0) {
+    fun acceptWaveform(samples: FloatArray, sampleRate: Int) =
+        acceptWaveform(ptr, samples, sampleRate)
+
+    fun inputFinished() = inputFinished(ptr)
+
+    protected fun finalize() {
+        if (ptr != 0L) {
+            delete(ptr)
+            ptr = 0
+        }
+    }
+
+    fun release() = finalize()
+
+    private external fun acceptWaveform(ptr: Long, samples: FloatArray, sampleRate: Int)
+    private external fun inputFinished(ptr: Long)
+    private external fun delete(ptr: Long)
+
+    companion object {
+        init {
+            System.loadLibrary("sherpa-onnx-jni")
+        }
+    }
+}